S-Space College of Medicine/School of Medicine (의과대학/대학원) Dept. of Medicine (의학과) The Seoul Journal of Medicine The Seoul Journal of Medicine Vol. 27 No.1 (1986)
Morphological Development of the Human Fetal Lung
한국인 태아폐(胎兒肺)의 형태학적 발육에 관한 연구
- Lee, Hoan Jong; Chi, Je G.; Ko, Kwang Wook
- Issue Date
- Seoul J Med, Vol.27 No.1, pp. 75-90
- The morphological development of the human fetal lung was studied analysing
a total of 198 human fetal lungs, including lungs of 16 embryos.
The weight of the lung increased progressively from 0.7 gm at 9-12 weeks of gestation to
45.2 gm at 37-40 weeks, and the right lung constituted 54 % of total lung weight. The lung,
fixed in the inflated state with negative pressure of 24-25 em H20 , increased rapidly in its
volume at 24-25 weeks of gestation, coinciding with the development of saccules. Reconstruction
of the embryonal lungs revealed the presence of lung buds at 4 weeks, stem bronchi at 5
weeks, segmental bronchi at 6 weeks, and subsegmental bronchi thereafter.
Histological characteristics were analysed with special emphasis on sequential development
of the functioning respiratory units. The period of 4-8 weeks was characterized by budding of
large bronchi and appearance of pleura and lobar pattern. During the period of 9-16 weeks,
conducting airways were laid down associated with development of cilia and mucous glands.
At the period of 17 -28 weeks acinar canals were proliferating and were followed by flattening
of epithelium and vascularization. Well developed saccules appeared by the end of this period.
During the period of 29-36 weeks, progressive thinning of septa was noted, accompanied by
segmentation of saccules by developing secondary crests. As a result well developed alveoli
with delicate septum and a single capillary system could be identified at the period of 37 -40
The height of the epithelium at the terminal buds showed gradual decrease from 36 f1 m at
5 weeks to 5.8 J1 m at 21 weeks of gestation.